From: Eugene Leitl (eugene.leitl@lrz.uni-muenchen.de)
Date: Wed Sep 06 2000 - 10:02:44 MDT
Michael S. Lorrey writes:
>
> Actually, for thin film amorphous, 10% is about exactly what the conversion
> efficiency is. I was wondering where you get your 'insolation' figure from. The
True, but you can get 20% panels, too, and more, if price is
irrelevant (~32% is about the best we can get iirc with multilayer
GaAs). With 10% I'm operating on the low end of the efficiency
spectrum, not coincidentially the best efficiency in wattage/$
produced.
> atmosphere cuts solar flux from just over 1.4 kw/m^2 down to just over 1 kw/m^2.
The insolation figure is totally ad hoc, since I don't have access to
my library, and a websearch via dialup in Krautland is a bear. I just
thought that 0.5 kW/m^2 on the average over a 10 h period in
California-type area is the about the right ballpark figure, if the
solar flux constant is 1.3 kW/m^2. I would of course welcome seeing
real numbers.
> > 2) solar cells do not require direct sunlight to generate
> > juice. diffuse daylight does nicely, especially when we're talking
> > about amorphous cells.
>
> Sure, but their efficiency decreases as flux decreases, and total flux does
> decrease with diffusion, as visible is converted to IR. If your flux drops by
I thought thin-film amorphous did at least NIR rather well.
> half due to diffusion by cloud cover, and the efficiency drops as well as flux
> drops, your output decreases markedly.
I did not know the average number of cloudy days in California, and
just took 365, assuming the few 10 days would not make a difference,
as other parameters have been chosen rather conservatively, and this
is a back of the envelope estimate.
Nitpicker!
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